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Chugging on cold startup
Posted by: mistertudball ()
Date: October 06, 2017 02:14PM

Ever since I got my '66 110 back from a shop (that I don't really trust anymore), upon cold start it fires up right away to a normal high idle, then in a few seconds devolves into chugging as if not firing on all six. This black soot now appears under the tailpipe, and it smells pretty strong although I can't really see smoke in the garage. By the time I'm out of the neighborhood (a mile or so) the engine runs fine and continues to until cold started again. The shop replaced both carbs (with Clarks) trying to solve a hesitation issue, if that helps. Any ideas what is wrong and could a mechanical neophyte fix it? I really don't want to take it back to them.

-----------------------------

Dave
Columbus, OH

'66 Monza convertible
'73 Eldorado convertible

[get.google.com]

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Re: Chugging on cold startup
Posted by: MattNall ()
Date: October 06, 2017 02:18PM

Chokes too rich!! Just shorten the rods 2 turns..





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Chugging on cold startup
Posted by: corventure Dave ()
Date: October 06, 2017 03:24PM

Sounds like one of the choke break vacuum pull off's has failed. Check to see if they will hold vacuum. Easy to do. Remove the hose. Push in the tab that goes to the choke arm, Cover the hose port and release the tab. If on one side the diaphragm does not hold vacuum, you can have one over rich choke.
This will clear up when the bi-metal chokes pull both carb valves to full open and the engine is warmed up. But it sounds like you have a classic case of a choke break diaphragm failure.

Corventure Dave

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Re: Chugging on cold startup
Posted by: steve c goodman ()
Date: October 06, 2017 03:52PM

OR choke pulloff links not adjusted correctly.

best wishes, Steve
Rear Engine Spec. Inc. Golden, Colo.

1962 spyder 3.0L turbo 1965 Crown V8
1967 monza 110/4 1968 monza 110/4
1971 amante gt 110/4
CORSA/RMC/PPCC

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Re: Chugging on cold startup
Posted by: mistertudball ()
Date: October 06, 2017 04:20PM

Pulling out my manual tomorrow to see what these ideas look like in daylight. I don't know a choke pulloff from an artichoke but can probably figure it out. Thanks!

-----------------------------

Dave
Columbus, OH

'66 Monza convertible
'73 Eldorado convertible

[get.google.com]

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Re: Chugging on cold startup
Posted by: gregb ()
Date: October 06, 2017 04:33PM

My 65 did the same thing after rebuild and as Steve said the choke pull off link needed to be adjusted, solved the issue with mine.

Gregb

Alberta Canada
61 Canadian Lakewood
62 Spyder Triple Black Convertible
65 Corsa Coupe

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Re: Chugging on cold startup
Posted by: steve c goodman ()
Date: October 06, 2017 04:43PM

Follow Dave's advice first and check the diaphrams before you check adjustments

best wishes, Steve
Rear Engine Spec. Inc. Golden, Colo.

1962 spyder 3.0L turbo 1965 Crown V8
1967 monza 110/4 1968 monza 110/4
1971 amante gt 110/4
CORSA/RMC/PPCC

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Re: Chugging on cold startup
Posted by: mistertudball ()
Date: October 07, 2017 03:35PM

I know this problem is simple but just don't feel comfortable (or knowledgeable) enough to proceed. I read the manual (tune-up and carb) and even searched YouTube but I just don't get it. Took the air cleaner off and fiddled with both carbs but just know I'll f-it-up worse. Thanks for all your suggestions.

-----------------------------

Dave
Columbus, OH

'66 Monza convertible
'73 Eldorado convertible

[get.google.com]

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Re: Chugging on cold startup
Posted by: flamingchariots ()
Date: October 07, 2017 09:00PM

Do you see the white plastic thing with the rubber hose attached?
That's the choke pull-off.
Now do the test that Corventure Dave explained!
You don't even need to disconnect the link; remove rubber hose from the white plastic, push the tab in, and cover the exposed tube with your index finger.
If the tab stays in, it's OK, if it's not holding vacuum, it is easy to replace.





Kevin
Medina, OH

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Re: Chugging on cold startup
Posted by: mistertudball ()
Date: October 08, 2017 07:54AM

OK, gotta ask the stupid questions:

I assume the engine should be running?
Should it be hot or cold?
By "tab" do you mean the metal bar that sticks out of the pull-off?
And I do this to both carbs?

If they're OK, what exactly did Matt mean by two turns to shorten the rods? What gets turned?

-----------------------------

Dave
Columbus, OH

'66 Monza convertible
'73 Eldorado convertible

[get.google.com]

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Re: Chugging on cold startup
Posted by: Wagon Master ()
Date: October 08, 2017 08:21AM

Yes that is the tab we are talking about.
Engine off and completely cold.
Depress throttle fully and release. Do choke plates completely close?
If no, lengthen the long thin choke thermostat rod coming out of the head by unscrewing until plates just close.
1. Unhook rubber line at the choke pull off.
2. Push the tab back into the pulloff. Put finger over hose connection and release tab. Does it stay retracted? Yes? Good. No? replace pulloff.
3. With tab depressed slide a 3/16" drill bit between carb. body and bottom of choke plate. Sloppy fit? Lengthen short rod between pulloff and choke plate. Tight fit? Shorten rod.
Do this to both carbs. Also with tab depressed, fast idle step cam on side of carb. should be on 2nd highest step.
All this and much more is outlined in the service manual and Bob Helts book. Give it a shot and try something. Unless you bend the bejesus out of the linkages you can't mess things up that can't be undone.


'64 Monza Coupe 140 4 speed
'61 700 Lakewood 95 4 speed
'69 Monza Convert. 140 Auto.

Been aircooled since 1973
Northwest Ohio

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Re: Chugging on cold startup
Posted by: steve c goodman ()
Date: October 08, 2017 08:52AM

Dave I looked in COMMUNIQUE and there are 5 clubs listed in Ohio. One of those has got to be in a town the size of Columbus. At the very least there are CORSA members in your area. If you join and find others to help guide you with understanding the mechanics of our cars
it would help you.

best wishes, Steve
Rear Engine Spec. Inc. Golden, Colo.

1962 spyder 3.0L turbo 1965 Crown V8
1967 monza 110/4 1968 monza 110/4
1971 amante gt 110/4
CORSA/RMC/PPCC

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Re: Chugging on cold startup
Posted by: mistertudball ()
Date: October 08, 2017 09:39AM

I pushed the gas pedal to the floor yesterday and both plates closed completely. And I just did the tab/hose test, pushing the tab in, then covering the hose connector with my finger. Both carb tabs stayed in until I removed my finger and they then popped back out, So that's OK, right?


By the way, Steve. I'm a member of the local Corvair club and they're nice people but haven't been that helpful in things mechanical.

-----------------------------

Dave
Columbus, OH

'66 Monza convertible
'73 Eldorado convertible

[get.google.com]

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Re: Chugging on cold startup
Posted by: MattNall ()
Date: October 08, 2017 09:43AM

With that test successful...

Just do what I said in my first reply.





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Chugging on cold startup
Posted by: RexJohnson ()
Date: October 08, 2017 10:01AM

If the car starts good and then after a few seconds it starts to stumble the chock pull-offs need to open the chocks a little more as Steve said in his first post. This sounds like the original complaint. If the car starts good and then after a few seconds it dies then the pull-offs are probably pulling the chocks open to far. If the car doesn't start good then check the chock adjustment as Matt is talking about.

RJ tools
Salem,Oregon

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Re: Chugging on cold startup
Posted by: MattNall ()
Date: October 08, 2017 10:28AM

Folks... Mr. TB is not comfortable under the hood...

The choke rod is the simple / temp fix.... IMO..





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Chugging on cold startup
Posted by: mistertudball ()
Date: October 08, 2017 10:29AM

The 3/16 drill bit just fit on the right carb when holding in the tab but it is too tight to pass by on the left carb. If I'm reading the manual correctly that means I have to actually bend metal. Gulp.

-----------------------------

Dave
Columbus, OH

'66 Monza convertible
'73 Eldorado convertible

[get.google.com]

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Re: Chugging on cold startup
Posted by: mistertudball ()
Date: October 08, 2017 10:50AM

But exactly how do I shorten the rods two turns, Matt? And why is it temporary? The manual is rather confusing but it sounds like I have to actually bend metal linkage pieces to adjust them.

And Rex. It's Door #1, the car fires up right away and in a few seconds starts stumbling or chugging. Does not die or come close.

-----------------------------

Dave
Columbus, OH

'66 Monza convertible
'73 Eldorado convertible

[get.google.com]

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Re: Chugging on cold startup
Posted by: MattNall ()
Date: October 08, 2017 11:04AM

If you do not feel comfortable bending the "Pulloff" Linkage to get the proper opening...

Then on THAT LEFT carb look to the rear of the carb and you'll see an 3/16" rod with ONE bend in it... approx. 45 degrees..

Look at the bottom of the rod where it enters the head... you may see the threads...

At the top of it on the chokes shaft is a clip.... pay attention to how it fits...

Remove it and screw the angled rod DOWN / CW 1 or 2 turns... your choice...

Carefully re-install clip.

Put air filter back on and IF you have not started it this am.... do so and see how it acts...

If you have started it already.... you'll need to wait until tomorrow morning to see how it works when engine is cold from setting overnight.





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Chugging on cold startup
Posted by: Richard ()
Date: October 08, 2017 11:48AM

Don't go bending anything until you understand what the problem actually is.

>>upon cold start it fires up right away to a normal high idle, then in a few seconds devolves into chugging as if not firing on all six.<<

That pull-off adjustment is normally a bench adjustment. At this point it would be advisable to assume Clark's provided you with the correct adjustments that are made before the carb is installed.

Carbs are not plug-n-play, as many people mistakenly assume. The choke rods that Matt mentioned are adjusted with the carbs installed, but not running. Idle speed adjustment, mixture adjustment are performed with the carbs installed and the engine running.

A slight miss adjustment of that pull-off rod is not going to make a major drivability issue.

Remove the air cleaner. With the engine cold, both choke plates should be wide open, standing vertically. Move the throttle cross shaft slightly and both choke plates should snap closed. At this time the throttle linkage will be held slightly open by the high-speed idle tab.

The choke rod is not adjusted by bending. Disconnect the rod end and screw the rod UP or DOWN by spinning it in a wide arc. The height of the rod should be made so that it holds the choke plate, just barely closed.

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